ST3.5 self-tapping screws

sheet-metal (ISO 1478)

5 documented uses, taken from manufacturer catalogs, service manuals and teardowns.

Pilot hole

2.9-3.2 mm in 1.0-2.0 mm steel

Too tight and the head snaps or the boss splits; too loose and the thread strips on the first removal.

Affiliate links — they cost you nothing extra and keep this database free.

Avoid repeated disassembly; thread wears down in thin sheet metal (clearance hole required).
Most TV, appliance, HVAC and power-tool service documents list only a driver type or a part number, never a thread size - so a screw kit sold as 'fits brand X' is usually a seller's guess, not an OEM spec. Measure the old screw before buying.